On twisted Fourier analysis and convergence of Fourier series on discrete groups

We study norm convergence and summability of Fourier series in the setting of reduced twisted group $C^*$-algebras of discrete groups. For amenable groups, F{\o}lner nets give the key to Fej\'er summation. We show that Abel-Poisson summation holds for a large class of groups, including e.g. all Coxeter groups and all Gromov hyperbolic groups. As a tool in our presentation, we introduce notions of polynomial and subexponential H-growth for countable groups w.r.t. proper scale functions, usually chosen as length functions. These coincide with the classical notions of growth in the case of amenable groups.Comment: 35 pages; abridged, revised and update

Mechanical assist in cardiac arrest: Optimising circulatory support. Experimental studies.

Introduction: Mechanical circulatory support (MCS) may be useful in cardiac arrest (CA), both in- and out- of hospital. However, efficacy and survival benefit has been difficult to evaluate compared to standard cardiopulmonary resuscitation. In three experimental studies we aimed to assess different modes of MCS during CA in providing adequate organ perfusion and systemic circulation and identify predictors of sustainable post-CA heart function. Different theoretical assumptions were the background for analysis in the three study protocols performed as acute experiments in anaesthetized pigs: Paper I: A major limitation to the effectiveness of a LVAD alone during CA is the lack of left ventricular (LV) filling due to minimal pulmonary circulation. We therefore wanted to assess if the combination of a left- and right ventricular assist device (BIVAD/BiPella) was beneficial as circulatory support versus a LVAD alone. Paper II: ECMO has the potential to replace systemic circulation during CA. However, concerns have been voiced regarding retrograde flow-delivery and effect on the myocardium during circulatory collapse. Based on results from Paper I we optimized BiPella support aiming to improve and maintain acceptable coronary perfusion pressure, believing this could potentially rectify the poor outcome of BIVAD/BiPella in Paper I if successful. Thus, in Paper II we compared the efficacy of balanced biventricular circulatory assist with extracorporeal membrane oxygenation (ECMO). Paper III: Pressure build-up in the left ventricle during cardiac arrest may be detrimental during extracorporeal cardiopulmonary resuscitation (ECPR) as indicated in Paper II. Therefore, we wished to investigate if unloading (venting) the left ventricle using add-on LVAD could be of benefit. However, the ideal flow-contributions of each assist device when combining LVAD and ECMO during ECPR in is not known. We therefore wanted to compare ECMO with standard or reduced flow and add-on LVAD versus ECMO alone. Finally, we wished to assess the contribution of add-on LVAD regarding pulmonary flow. Materials and methods: The animal experiments were performed at the Vivarium, University of Bergen, and protocols were approved by the Norwegian Animal Research Authority or by the Norwegian Food Safety Authority. Paper I and II were performed with percutaneous techniques. The final experiment was an open chest model. All protocols followed a similar timeline: 1. Anaesthesia and instrumentation of the pig. 2. Baseline evaluation. 3. Induction of CA by application of a 9V DC battery to the myocardium. 4. Immediate initiation of mechanical circulatory support (MCS). 5. Three attempts of cardioversion at the end of the CA period. 6. If successful return of spontaneous circulation (ROSC) was achieved, unsupported observation (Paper II and Paper III). Comparisons between intervention groups: 1. Haemodynamics (during and after CA). 2. Organ tissue blood flow rate (organ perfusion) and device output as calculated from fluorescent microspheres. 3. Arterial blood gases and biomarkers. 4. ROSC. 5. Sustained cardiac function post-ROSC (Paper II and Paper III). In Paper I, twenty animals were randomized in two groups receiving circulatory support either by the Impella CP alone (LVAD) or in combination with the Impella RP (BIVAD/BiPella) during 30 minutes of CA. In Paper II, twenty pigs were randomized to receive MCS either by BiPella or by extracorporeal membrane oxygenation (ECMO) during 40 minutes of CA. If ROSC was successful, animals were observed for 60 minutes unsupported. In Paper III, twenty-four animals were randomized in three groups. Extracorporeal cardiopulmonary resuscitation (ECPR) in Group 1 was provided by ECMO with standard-flow and add-on Impella CP. In Group 2: ECMO with reduced flow combined with Impella CP. In Group 3, animals were supported by standard-flow ECMO alone. ECPR lasted for 60 minutes. If ROSC was successful, 180 minutes unsupported observation followed. Results: Paper I demonstrated that BIVAD/BiPella provides superior circulatory support and perfusion for peripheral organs (including the brain) related to higher LVAD output and increased central aortic pressure compared to LVAD alone. However, myocardial perfusion was related to the pressure difference between mean aortic pressure and mean left ventricular pressure during cardiac arrest. Myocardial perfusion was inferior with BiPella resulting in significantly fewer ROSC (5/10 vs 10/10, p = 0.033) despite significantly higher etCO2 (p = 0.029). Paper II showed that balancing RVAD and LVAD to ensure acceptable coronary perfusion pressure and concomitant LVAD output was feasible, also sustaining vital organ perfusion. However, ECMO provided a more optimal systemic circulatory support. Device output and mean aortic pressure were increased with subsequent improved peripheral tissue perfusion reflected by reduction of s-lactate. In animals where sufficient myocardial perfusion pressure (mean aortic pressure – mean LV pressure > 10-15 mmHg) could not be achieved, perfusion (ml/min/g) was reduced in the subendo- and midmyocardium, averaging 0.59 ± 0.05 vs. 0.31 ± 0.07, (p = 0.005) and 0.91 ± 0.06 vs 0.65 ± 0.15 (p = 0.085), but not in the subepicardium (1.02 ± 0.07 vs 0.86 ± 0.17, p = 0.30) irrespective of group. These subjects also had inferior post-ROSC cardiac function. Paper III showed that add-on LVAD improved haemodynamics compared with ECMO alone during refractory CA. Add-on LVAD could not substitute a reduced ECMO-flow. Three animals with reduced ECMO flow and adjunctive Impella support did not achieve ROSC. With ECMO alone, ROSC was obtained in all animals. However, 4/8 died post-ROSC due to development of cardiogenic shock. In the remaining 21 animals, 17 animals had sustained cardiac function at study termination 3 h after ROSC. Animals without sustained cardiac function (7/24) had reduced mAP (p < 0.001), CPP (p = 0.002) and mPAf (p = 0.004) during CA and ECPR. Conclusions: Paper I: Biventricular support during cardiac arrest was associated with high intraventricular pressure in the left ventricle resulting in decreased myocardial perfusion pressure, reduced myocardial tissue blood flow rate and subsequent reduction in ROSC. Paper II: Myocardial perfusion and sustained cardiac function were related to myocardial perfusion pressure during VF irrespective of MCS (ECMO and balanced biventricular support). Balanced biventricular support maintained lower intraventricular pressure compared to ECMO. Paper III: Add-on LVAD improved haemodynamics compared to ECMO alone. An add-on Impella could not substitute a reduction in ECMO flow. Increased mean aortic pressure, myocardial perfusion pressure and mean pulmonary artery flow were related to sustained cardiac function and ROSC.Doktorgradsavhandlin

Calling on a million minds for community annotation in WikiProteins.

WikiProteins enables community annotation in a Wiki-based system. Extracts of major data sources have been fused into an editable environment that links out to the original sources. Data from community edits create automatic copies of the original data. Semantic technology captures concepts co-occurring in one sentence and thus potential factual statements. In addition, indirect associations between concepts have been calculated. We call on a 'million minds' to annotate a 'million concepts' and to collect facts from the literature with the reward of collaborative knowledge discovery. The system is available for beta testing at http://www.wikiprofessional.org.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

The FAIR Guiding Principles for scientific data management and stewardship

There is an urgent need to improve the infrastructure supporting the reuse of scholarly data. A diverse set of stakeholders—representing academia, industry, funding agencies, and scholarly publishers—have come together to design and jointly endorse a concise and measureable set of principles that we refer to as the FAIR Data Principles. The intent is that these may act as a guideline for those wishing to enhance the reusability of their data holdings. Distinct from peer initiatives that focus on the human scholar, the FAIR Principles put specific emphasis on enhancing the ability of machines to automatically find and use the data, in addition to supporting its reuse by individuals. This Comment is the first formal publication of the FAIR Principles, and includes the rationale behind them, and some exemplar implementations in the community

‘If you’ve lost your personality, there’s no point in changing the valve’—a qualitative study of older adults’ attitudes towards treatment of aortic stenosis with comorbid dementia

Objectives: Due to prognostic uncertainty and limited decision-making capacity, the choice to perform transcatheter aortic valve implantation (TAVI) in patients with severe aortic stenosis (AS) and comorbid dementia is challenging. This study explores older adults’ perspectives on complex decision-making preceding TAVI in the hypothetical setting of comorbid dementia. Design: Qualitative study entailing semistructured interviews. Analysis was by systematic text condensation. The interview guide addressed their attitudes regarding treatment dilemmas before TAVI in patients living with dementia. Setting: Patients were recruited from the TAVI outpatient clinic at a university hospital performing TAVI. Participants: A purposive sample of 10 older adults (5 women) with AS and without dementia (range 77–94 years), where 8/10 had undergone TAVI were included. Results: Three main challenges were identified: (1) Risk assessment. Participants found it hard to compare the burden of aortic stenosis vs dementia. They acknowledged the dilemma of implanting a new heart valve to achieve symptom relief while risking severe dementia in the future due to prolonged life span. (2) Autonomous capacity. A profound uncertainty was described regarding who should participate in decision-making if the person was incapacitated due to dementia. (3) Customised information. Participants advocated for thorough information describing facts and uncertainty, aiming to protect and support the person living with dementia. Conclusion: Older adults with severe aortic stenosis find it hard relating to dilemmas arising from providing TAVI in patients living with dementia. There is a need for tailor-made information to support autonomy and decision-making under uncertainty

Anxiety and depression in patients aged 80 years and older following aortic valve therapy. A six‑month follow‑up study

Background Little is known about mental health following advanced cardiac procedures in the oldest patients. Aims To study changes in anxiety and depression from baseline to one- and six-month follow-up in older patients following transcatheter aortic valve implantation (TAVI) or surgical aortic valve replacement (SAVR). Methods Prospective cohort study of patients ≥ 80 years undergoing elective TAVI or SAVR in a tertiary university hospital. Anxiety and depression were assessed with the Hospital Anxiety and Depression Scale. Differences between TAVI/SAVR were analyzed using Welch’s t test or chi-squared. Changes over time and group differences were established with longitudinal models using generalized least squares. Results In 143 patients (83.5 ± 2.7 years), 46% (n = 65) received TAVI. Anxiety was identified in 11% of TAVI patients at baseline. One- and six-months later, percentages were 8% and 9%. In SAVR patients, 18% had baseline scores indicating anxiety. One and six-months later, percentages were 11% and 9%. Depression was identified in 15% of TAVI patients. One- and six-months later, percentages were 11% and 17%. At baseline, 11% of SAVR patients had scores indicating depression. One- and six-months after SAVR, percentages were 15% and 12%. Longitudinal analyses showed reductions (P < 0.001) in anxiety from baseline to one-month, and stable scores between one- and six-months for both treatment groups. There was no change over time for depression among treatment groups (P = 0.21). Discussion and conclusions SAVR or TAVI in patients ≥ 80 years was associated with anxiety reduction between baseline and follow-up. For depression, there was no evidence of change over time in either treatment group.publishedVersio

Baseline frailty status and outcomes important for shared decision-making in older adults receiving transcatheter aortic valve implantation, a prospective observational study.

AIMS The objective of this study was to examine baseline frailty status (including cognitive deficits) and important clinical outcomes, to inform shared decision-making in older adults receiving transcatheter aortic valve implantation (TAVI). METHODS AND RESULTS We conducted a prospective, observational study of 82 TAVI patients, recruited 2013 to 2015, with 2-year follow-up. Mean age was 83 years (standard deviation (SD) 4.7). Eighteen percent of the patients were frail, as assessed with an 8-item frailty scale. Fifteen patients (18%) had a Mini-Mental Status Examination (MMSE) score below 24 points at baseline, indicating cognitive impairment or dementia and five patients had an MMSE below 20 points. Mean New York Heart Association (NYHA) class at baseline and 6 months was 2.5 (SD 0.6) and 1.4 (SD 0.6), (p < 0.001). There was no change in mean Nottingham Extended Activities of Daily Living (NEADL) scale between baseline and 6 months, 54.2 (SD 11.5) and 54.5 (SD 10.3) points, respectively, mean difference 0.3 (p = 0.7). At 2 years, six patients (7%) had died, four (5%, n = 79) lived in a nursing home, four (5%) suffered from disabling stroke, and six (7%) contracted infective endocarditis. CONCLUSIONS TAVI patients had improvement in symptoms and maintenance of activity of daily living at 6 months. They had low mortality and most patients lived in their own home 2 years after TAVI. Complications like death, stroke, and endocarditis occurred. Some patients had cognitive impairment before the procedure which might influence decision-making. Our findings may be used to develop pre-TAVI decision aids

Genome-wide association study of susceptibility to hospitalised respiratory infections

Background: Globally, respiratory infections contribute to significant morbidity and mortality. However, genetic determinants of respiratory infections are understudied and remain poorly understood. Methods: We conducted a genome-wide association study in 19,459 hospitalised respiratory infection cases and 101,438 controls from UK Biobank (Stage 1). We followed-up well-imputed top signals from our Stage 1 analysis in 50,912 respiratory infection cases and 150,442 controls from 11 cohorts (Stage 2). We aggregated effect estimates across studies using inverse variance-weighted meta-analyses. Additionally, we investigated the function of the top signals in order to gain understanding of the underlying biological mechanisms. Results: From our Stage 1 analysis, we report 56 signals at P&lt;5×10 -6, one of which was genome-wide significant ( P&lt;5×10 -8). The genome-wide significant signal was in an intron of PBX3, a gene that encodes pre-B-cell leukaemia transcription factor 3, a homeodomain-containing transcription factor. Further, the genome-wide significant signal was found to colocalise with gene-specific expression quantitative trait loci (eQTLs) affecting expression of PBX3 in lung tissue, where the respiratory infection risk alleles were associated with decreased PBX3 expression in lung tissue, highlighting a possible biological mechanism. Of the 56 signals, 40 were well-imputed in UK Biobank and were investigated in Stage 2. None of the 40 signals replicated, with effect estimates attenuated. Conclusions: Our Stage 1 analysis implicated PBX3 as a candidate causal gene and suggests a possible role of transcription factor binding activity in respiratory infection susceptibility. However, the PBX3 signal, and the other well-imputed signals, did not replicate in the meta-analysis of Stages 1 and 2. Significant phenotypic heterogeneity and differences in study ascertainment may have contributed to this lack of statistical replication. Overall, our study highlighted putative associations and possible biological mechanisms that may provide insight into respiratory infection susceptibility.</p

Comment: The FAIR Guiding Principles for scientific data management and stewardship

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